1. Field of the Invention
The invention relates to a recliner. More specifically, the invention relates to a recliner that connects a seat back to a base on a floor such that the backrest angle of the seat back is adjustable.
2. Description of Related Art
In a vehicle seat of the related art, a seat back is connected to a seat cushion via a recliner such that the backrest angle is adjustable (see Japanese Patent Application Publication No. 2009-279184 (JP 2009-279184 A)). In the recliner, disk-shaped internal gear and external gear are assembled together such that they rotate relative to each other while changing a mesh position where the internal gear and the external gear mesh with each other. By use of a coupling mechanism mounted between the internal gear and the external gear, the internal gear and external gear are pressed against each other in a radial direction so that their relative rotation is inhibited, or pushed and rotated in such a direction as to change the mesh position.
The external gear and the internal gear are assembled together, with a cylindrical retaining member mounted across their radially outer portions, such that the gears are inhibited from being disengaged from each other or falling off in the axial direction. Also, the external gear and the internal gear are firmly and integrally joined to a side frame of the seat back and a side frame of the seat cushion, by means of dowels formed on axially outer surfaces of the gears to protrude from these surfaces. Namely, each of the dowels is fitted in and welded to a corresponding one of dowel holes formed in the side frame of the seat back or the side frame of the seat cushion.
However, according to the related art, the dowels are formed in the vicinity of outer peripheral portions of the external gear and the internal gear. Therefore, when each of the dowels is fitted in and welded to the corresponding dowel hole of the side frame, a backing portion (a radially outer portion of the external gear or internal gear) to be placed against the rear side of the side frame is insufficient, and the side frame may burn through during welding if the thickness of the side frame is small.